Invasive and Non-Invasive Ventilation in Patients With COVID-19

Abstract

Background: The reported high mortality of COVID-19 patients in intensive care has given rise to a debate over whether patients with this disease are being intubated too soon and might instead benefit from more non-invasive ventilation.

Methods: This review is based on articles published up to 12 June 2020 that were retrieved by a selective literature search on the topic of invasive and non-invasive ventilation for respiratory failure in COVID-19. Guideline recommendations and study data on patients with respiratory failure in settings other than COVID-19 are also considered, as are the current figures of the intensive care registry of the German Interdisciplinary Association for Intensive Care and Emergency Medicine (Deutsche Interdisziplinäre Vereinigung für Intensiv- und Notfallmedizin).

Results: The high mortality figures among patients receiving invasive ventilation that have been reported in studies from abroad cannot be uncritically applied to the current situation in Germany. Study data on ventilation specifically in COVID-19 patients would be needed to do justice to the special pathophysiology of this disease, but such data are lacking. Being intubated too early is evidently associated with risks for the patient, but being intubated too late is as well. A particularly im - portant consideration is the potential harm associated with prolonged spontaneous breathing, with or without non-invasive assistance, as any increase in respiratory work can seriously worsen respiratory failure. On the other hand, it is clearly unacceptable to intubate patients too early merely out of concern that the medical staff might become infected with COVID-19 if they were ventilated non-invasively.

Conclusion: Nasal high flow, non-invasive ventilation, and invasive ventilation with intubation should be carried out in a stepwise treatment strategy, under appropriate intensive-care monitoring and with the observance of all relevant anti-infectious precautions. Germany is better prepared that other countries to provide COVID-19 patients with appropriate respiratory care, in view of the high per capita density of intensive-care beds and the availability of a nationwide, interdisciplinary intensive care registry for the guidance and coordination of intensive care in patients who need it.

Figure 1

Self-inflicted lung injury A central role is played by the high respiratory drive of the spontaneously breathing and conscious patient, with or without NIV, with increasingly impaired gas exchange and restricted respiratory mechanics (19). The consequent high respiratory work may then lead to high, regionally variable, fluctuations in transpulmonary pressure. It is crucial to realize that struggling to breathe in results in a lowering of pleural pressure that exceeds the intravascular pressure decrease. With an additional elevation of intrathoracic blood volume on inspiration, this causes an increase in transmural pulmonary vascular pressure. The result is a higher risk of pulmonary edema, especially in an already damaged lung (capillary leakage). Completing the vicious circle, this then leads to further impairment of breathing mechanics with decreased compliance and restriction of gas exchange, which in turn favors shortness of breath and thus a further increase in respiratory work. NIV, Non-invasive ventilation

Figure 2

The possible causes of classic ARDS in patients with COVID-19 pneumonia

Figure 3

Possible instrument-based treatment escalation in the case of acute respiratory insufficiency as a result of COVID-19, as recommended in the position paper of the German Respiratory Society (DGP) (1). * Wearing personal protective equipment as recommended by the Robert Koch Institute. COPD, chronic obstructive pulmonary disease; CPAP, continuous positive airway pressure; DNI, do not intubate; FiO2, inspiratory oxygen fraction; kPa, kilopascal; NIV, non-invasive ventilation; PaO2, oxygen partial pressure; PEEP, positive end-expiratory pressure; RR, respiratory rate; SpO2, peripheral oxygen saturation; Vt, tidal volume (Reproduced by kind permission of Georg Thieme Verlag)